Process of dehydrating oils



1,639,325 Aug 16v 1927' s. BORN ET AL PROCESS OF DEHYDRATING OILS Filed April 20, 1920 SALT WA TE Patented Aug. A1e, i927.

UNITED STATES assenza PATENT OFFICE.

SIDNEYBoRN AND HOWARD EDGAR RONNETTE, or BARTLEsvILLEoxLAHoMA, AND

JonN CHARLES WALKER, or ELDoRADo, xANsAs, AssIeNoRs To EMPIRE GAso- LINE COMPANY, or DovER, DELAWARE, A coRroRA'rIoN or DELAWARE., l

PROCESS OE DQEHYDRATING OILS.

Application mea Apen 20,1920. serial Na. 375,222

This invention `relates to a process of dehydrating oils and more particularly to a process of separating water from crude petroleum containing natural brine 1n the 5- form of suspended particles or of an emulsion of water in oil.

. Petroleum from wells in many oil producing localities carriesA with it large u'antitles of vsalt water which occurs in the oi producinfg formationv or in-strata above or below the oil producing formation, and which vbecomes mixed with and is'carried by the petroleuml as itV Hows from the well. This water, whichy usually contains chlorides, sul

phates, and other salts in solution, 1s disseminated thruout the'oil in a large number of particles varying in size from comparatively large drops which readily separate out of the mixture on standing, to m1- nnte particles of microscopic or nl tramicroscopic size which form a substantlally permanent emulsion with the oil. These minute particles do not separate 4from the body of oil even upon longstanding, but may be separated from some pes of emulsion by heat.-

ing or by 'the addition of substances of an alkaline nature which act to precipitate or settle the particles of water.

The Waterl precipitated in this manner frequentl does not separate as a. clear liquid but is mlxed with a large quantity of oil,

i* with which it forms a thick, semi-solid orl solid, mass, commonly known as bottom settlings or B. S. Thebottom'settlingsor B. S. has many ofthe properties of semisolid emulsions or gels and is apparently formed of minute particles of Water or'salt solution of microscopic or ultramicroscopic size surrounded -by films of oil adsorbed or 40 otherwise held to the surface of the particles of water or salt solution and forming a network Within which the particles are tenaciously held. This mixture of oil and water can not be broken up by the methods or means commonly employed to separate water from the body of oil, and because of its water contentl and itslack of fluidity can not be transported to refineries or refined. It not only involves a loss because of the oil it contains, but also constitutes a nuisance because of its offensive nature and of the diiculty of disposing of it.

The primary object of the .present invention is to provide a process by which amixture or emulsion of oil and water may be 65 separated into clear oil and Water.

Another object of the present inventionI islto provide a process of dehydrating oil by which the formation of bottom settlings or semi-solid emulsions is avoided and by which bottom l settlings maythemselves be broken up into clear oil and water.

' Another object of the invention is to provide a material by which an emulsion or suspension of Water in oil may be substantially completely removed from the oil.

When oil is treated by means of chemigals, the cost of the chemicals constitutes a large item of expense. This is true even in cases in which the quantit of the/chemicals ap- .70 pears to. be small re atively to the volume of the oil to be treated, because the quantities of oiltol be treated are so\enormous that a quantity "ofchemical equal to a very vsmall percent of the oil would be quite large in the aggregate.

A further 'object of the present invention is, therefore, to provide 'a process of dehydratig oils in which a quantity of reagent used inthe treatment is reduced to a minimum. f

A further object of the invention isto provvidean agent for precipitating and breaking up an emulsion of water in lpetroleum. v

With these and other objects in view, the invention consistsin the processdescribedf -in the following specification and defined in the claims.

.The'main steps of the process are illu's- 90 trated diagrammatically in the How Sheet shown in the accompanying drawings.

In the present invention,'the mixture or emulsion of oil" and water to be dehydrated is treated with a saline solution of .substantially the same composition and salt content `as that carried in suspension in the oil, and

which contains in addition a small quantity of sodium hydroxide. This solution of salts and hydroxide is most conveniently obtained by addingsodium hydroxide to "salt water which has been separated from the oil by a previous treatment with an alkali solution l or by adding sodium hydroxide to salt water which has been obtained by settling water from the oil coming from the wells. When the emulsion of oil and water is treated with valkali salt solution prepared in this manner,

- v posed by a second treatment with an additional quantity of the alkaline solution and heating to a somewhat higher temperature. The cause of this peculiar decomposing action of the salt and alkali and the manner f in which it acts on the dispersedparticles of water is not known with certainty. The' mixed solution appears to have a precipitating action due to the mutual discharge of the static electricity on the suspended particles of water, caused by the presence of hydroxyl ions, and in addition to have the property, due to the combined influence of the salts and hydroxyl ionsof altering the composition or character of the dividing rsurface between the oil and suspended water particles, or of changing the surface tension or other characteristics of the suspended particles so as to break up the adhering ilmsor network of oil enclosmg'the precipitated particles. and permit the particles to coalesce and unite into a single body.' This latter action appears to be due largely to the presence of the salts, as the hardness of the well water is not appreciably-affected by the addition of the'alkali. Its action is much different in this respect than that of a solution of alkali in soft water or in water which does not contain Inuchsalt in solution.

In order to. avoidv the use of an excessive y amount of alkali, all of the water which will separate from the oil without the addition of alkali is permitted to settle out of the mixture of oil and water before any alkaline solution is added. An' amount of sodium hydroxide is mixed with the separated salt solution to form a solution containing from .2 to .4 percent of sodium hydroxide. The alkali solution prepared in this manner is then mixed with oil from which all water which will readily separate by gravity has been removed and which still contains the more minute particles of salt solution forming a more or less permanent emulsion with the oil. The mixture of oil emulsion and alkali solution is then heated and the heated mixture allowed to stand, whereupon the sa` line solution separates from the main body of the oil as a comparatively clear liquid. Any emulsion which remains after this treatment is decomposed by a second treatment with an additional quantity of alkaline solution and heating to a higher temperature.

Referring to the flowl sheet shown in the accompanying drawings, the mixture of oil and water tobe treated is'run into a storage tank 10 in which the major portion of the, waterseparates as a clear liquid and is with drawn thru a draw-oli pipe 12. A portionV of the salt Water is taken from the pipe 12 through a branch pipe 14 to a mixing tank 16 in whichan amount of sodium hydroxide suiiicientto form a solution of from .2 to .4 per cent of sodium hydroxide is added. The

concentration of the sodium hydroxide in the solution may vary between these limits or may vary slightly fromlthese limits, but for the best results, should not be below .1 or above .5 per cent. y

The oil remaining after the withdrawal of water rom'the tank 10 contains salt water heldI as amore orless permanent emulsion which will not separate upon standing, is withdrawn through a draw-off pipe 18 and mixed with alkali. salt solution Withdrawn from the tank 16 through a draw-off pipe 20. The amount of alkali solution added tov the oil will vary, of course, with the nature of the emulsion and with 'the quantity of emulsion in the oil. An oil` containing approximately 10 per cent of emulsion will require a solution containing approximately 9 lbs. of sodium hydroxide for 100 bbls. of oil.

The mixture of oil and alkaline solution formed in the pipe 18 is passed through the heat receiving compartment of a number of `heat interchangers 22 in which it is heated by hot oil produced in later steps of the process. From the heat interchangers 22 the mixture of ol and alkali'solution passes through a pipe 24 to steam' heated coils 26 which are heated to a temperature of from 150 to 160o F. At this temperature the emulsion of oil and water is largely lbroken up and passes to 4a primary or low temperature settling tank 28 in which the water separates out leaving a body of oil substantially free from Water. The clear oily is then withdrawn from the tank 28 through a pipe 30 and passed through the heating compartments of the heat interchangers 22 in which it gives up I its heat `to the cold oil entering the interchangers`"'through the pipe 18. f heat interchangers 22, the oil flows through a pipe 32 tov water cooled coilsI 34: in which its temperature is vreduced t0 normal and then flows into a. lstorage tank 36.

The water remaining y'in the tank 28 after the removal of the oil may contain a small` amount of an emulsion or gel of water and oil. To remove the emulsiiied oil,- the water is withdrawn from the tank 28 through a pipe 38 to a trap 40 in which the clear water is separated from the gel or emulsion and returned through a pipe 42 to the mixing tank 1-6. By returning the water from the trap 40 to the tank 16, la large part of the alkali is returned to the process and saved. During the treatment of the oil, the alkali From the pounds and other impurities from the-oil and to become unfit for further use. When the solution becomes impregnated with impurities, it is, therefore, not returned to the mixing tank but is discarded.

The emulsion or gel remaining in the trap v changer 48 passes through a pipe 50 to steam heated coils 52. In the coils 52 the mixture .of oil and alkali solution is heated to ap proximately 180 F. by means of steam supplied froma pipe 54. By this second treatment substantially all of the emulsion is broken up into clear oil and water. The heated mixture of oil and alkaline solution is withdrawn from the heated coils'` 52 through a pipe 56 to a settling tank 58 in which the water or salt solution settles out of the mixtureleaving a clear body of oil..

The clear oil is removed from the tank'58 through 4a pipe 60 and passed through the heating compartment of the heat interchanger 48 giving up its heat to the cooler oil from the pipe 44. From the heat interchanger 48 the cooled oil passes through va pipe 62' to the pipe 32 in which it mixes with oil from the primary settling tank 28 and enters/the ycooling coils 34. In thecooling coils 34 the oil is reduced to normaltemperature and flows into the storage tank 36.

The' salt water remaining in the tank 58 after the removal of the oil is withdrawn through a pipe 64 "to centrifugals which remove 'any particles of oil which may be entrained therein, or maybe run directly to a Waste.

"By thus removing all ofthe water possible without the use of reagents before adding any reagent and -by progressively increasing the quantity and vconcentration of reagent in the treated mixture only after the removal of all the water possible with lower concentrations, the quantlty of oil and water, and accordingly the quantity of reagent used is vreduced to a minimum. By

re-using-the alkali solution until it becomes impregnated with-impurities a further saving of chemicals is effected and the consumption of chemicals is reduced to a minimum.

Having described the invention, what is claimed as new is:

1. A process of dehydrating petroleum which comprises separating water from said petroleum, adding'l a hydroxide of an alkali metal to said separated` water in an amount less than -that required. to substantially afect, the hardness of the lwater associated,v

with the oil, and mixing said alkali solution with said petroleum.

2. A process of dehydratingl petroleum` containing salt water which comprises forming a solution of an alkali hydroxide in salt Water of substantiallythe same composition as that contained in said oil, mixing with said oil saidalkali solution in an amount less than that required to substantially affect' the hardness of the water associated with the oil, heating said mixture and permitting the water -to settle out of s aid oil.

" 3. A process of separating water from a naturally occurring mixture of water and oil, which comprises adding to said mixture a solution of an alkali` hydroxide in'wa-ter 'of substantially the same composition as that contained in said oil, the amount of hydroxide in said solution bein insufficient to substantially affect the har ness of the water associated with the oil".

4. A process' of dehydrating` petroleum containing a saline solution in suspension which comprises mixin with said petroleum a saline solution of su stantially the same composition as that contained in suspension in the petroleum and containin in addition a vmaterial furnishing hydroxy ions in an amount such that it will not substantially affect the hardness of the saline solution associated with the oil.

5.1A process of separating salt water from petroleum which comprises mixing with said petroleum salt water of substantially the same composition as that contained in the petroleum and containing' in addition not more than .5 per cent of an alkali hydroxide.

6. 4A process of separating salt water from petroleum which com rises mixin with said petroleum a saline so utionof su stantially the same composition as that contained in the petroleum and containing, in addition,

not' less than .1 per cent nor more than '.5

per cent of sodium hydroxide.

7. A material for separating salt water ,y

from an emulsion of petroleum and salt water. which comprises salt water obtained from the said emulsion, and an alkali hydroxide to the extent of between .1 and .5 percent vof the solutionf 8. A process of dehydrating oils which comprises removin from the oil water which is separable hy gravity, dissolving a hydroxide of an alkali metal 1n a portion of said water, mixing said'alkali hydroxide solution with said separated oil, heating said mixture of oil and alkali solution to a proximately 150 to 160, F., removing t e oil and water thereby separated from the permanent emulsion, adding an additional quantity of alkali solution to the emulsion remaimng, heating said emulsion to aproximately 180 F., and separating the oil om the water of said heatedemulsion.

9. A process of dehydrating oils which comprises removing water from the oil, heat- ,ing said oil and water remaining in said oil to approximately 150 to. 160F4, removing the oil separating from the mixture upon Said heating, cooling said oil successively by al mixture of oil and alkali solution and by cold Water, separating the water from the mixture of oil and Water after said heating and using said Water in making up an alkali solution, adding said alkali solution to the emulsion remaining, heating said mixture ot emulsion and alkali tol'a-p- -proximately 180 F., and removing the water from the oil separated upon said second heating. y

10. A process of dehydrating oil which comprises mixing said oil with analkaline solution, containing from .l to per cent ofcaustic alkali, heating said mixture and .p elrmitting the water to separate from the o1 l 11. A process of dehydrating oil containing an emulsion of oil and salt Water which comprises adding to the oil a solution of a material furnishing hydroxyl ions dissolved in salt Waterof substantiallythe same composition as that contained in the emulsion, the amount of Isaid material beinginsuflicient to substantially affect the hardness of the water associated With the'oil. 1

12. The process of treating petroleum brine emulsion comprising separating brine and oil from an oil-brine emulsion and adding a solution'of said brine and an alkali to said emulsion, the amount of said solution being insufficient to substantially aii'ect' the hardness of the Water associated with the oil.

in testimony whereof We aiix our signatures.- .y y,

1 SIDNEY' BRN..

JOHN CHARLES WALKER. HOWARD EDG-AR BONNETTE. 

